Biotin deficiency and susceptibility to fatty liver and kidney syndrome in broiler chicks: reduced 6-phosphofructokinase (EC 2.7.1.11) activity but normal fructose 2,6-bisphosphate content in birds with hepatomegaly.

In two separate experiments, using different strains, broiler chicks were reared on either a commercial-type chick mash (control) or a fatty liver and kidney syndrome (FLKS)-inducing diet. In Expt a, chicks were killed on day 29 and in Expt b, on day 32. Body-weights and liver weights were measured, and values from those given the control ration used to construct a hepatomegaly index by employing a variant of linear discriminant analysis. Application of the index to FLKS birds revealed a statistically significant bimodal distribution of liver size. The birds with enlarged livers (high index) also possessed metabolic abnormalities in that 6-phosphofructokinase (EC 2.7.1.11; PFK-1) activity (measured at low substrate concentration) was depressed despite the presence of normal, or even slightly elevated fructose 2,6-bisphosphate concentration. This indicates the presence of an uncharacterized regulatory mechanism for PFK-1 in FLKS-susceptible birds.